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<div class="titlepage"><div><div><h4 class="title">
<a name="boost_asio.reference.co_spawn.overload4"></a><a class="link" href="overload4.html" title="co_spawn (4 of 6 overloads)">co_spawn (4
        of 6 overloads)</a>
</h4></div></div></div>
<p>
          Spawn a new coroutined-based thread of execution.
        </p>
<pre class="programlisting">template&lt;
    typename ExecutionContext,
    typename <a class="link" href="../Executor1.html" title="Executor requirements">AwaitableExecutor</a>,
    typename CompletionToken = <a class="link" href="../asynchronous_operations.html#boost_asio.reference.asynchronous_operations.default_completion_tokens"><span class="emphasis"><em>DEFAULT</em></span></a>&gt;
<a class="link" href="../asynchronous_operations.html#boost_asio.reference.asynchronous_operations.automatic_deduction_of_initiating_function_return_type"><span class="emphasis"><em>DEDUCED</em></span></a> co_spawn(
    ExecutionContext &amp; ctx,
    awaitable&lt; void, AwaitableExecutor &gt; a,
    CompletionToken &amp;&amp; token = <a class="link" href="../asynchronous_operations.html#boost_asio.reference.asynchronous_operations.default_completion_tokens"><span class="emphasis"><em>DEFAULT</em></span></a>,
    typename constraint&lt; is_convertible&lt; ExecutionContext &amp;, execution_context &amp; &gt;::value &amp;&amp;is_convertible&lt; typename ExecutionContext::executor_type, AwaitableExecutor &gt;::value &gt;::type  = 0);
</pre>
<h6>
<a name="boost_asio.reference.co_spawn.overload4.h0"></a>
          <span class="phrase"><a name="boost_asio.reference.co_spawn.overload4.parameters"></a></span><a class="link" href="overload4.html#boost_asio.reference.co_spawn.overload4.parameters">Parameters</a>
        </h6>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">ctx</span></dt>
<dd><p>
                An execution context that will provide the executor to be used to
                schedule the new thread of execution.
              </p></dd>
<dt><span class="term">a</span></dt>
<dd><p>
                The <a class="link" href="../awaitable.html" title="awaitable"><code class="computeroutput">awaitable</code></a>
                object that is the result of calling the coroutine's entry point
                function.
              </p></dd>
<dt><span class="term">token</span></dt>
<dd>
<p>
                The completion token that will handle the notification that the thread
                of execution has completed. The function signature of the completion
                handler must be:
</p>
<pre class="programlisting">void handler(std::exception_ptr);
</pre>
<p>
              </p>
</dd>
</dl>
</div>
<h6>
<a name="boost_asio.reference.co_spawn.overload4.h1"></a>
          <span class="phrase"><a name="boost_asio.reference.co_spawn.overload4.example"></a></span><a class="link" href="overload4.html#boost_asio.reference.co_spawn.overload4.example">Example</a>
        </h6>
<pre class="programlisting">boost::asio::awaitable&lt;void&gt; echo(tcp::socket socket)
{
  try
  {
    char data[1024];
    for (;;)
    {
      std::size_t n = co_await socket.async_read_some(
          boost::asio::buffer(data), boost::asio::use_awaitable);

      co_await boost::asio::async_write(socket,
          boost::asio::buffer(data, n), boost::asio::use_awaitable);
    }
  }
  catch (const std::exception&amp; e)
  {
    std::cerr &lt;&lt; "Exception: " &lt;&lt; e.what() &lt;&lt; "\n";
  }
}

// ...

boost::asio::co_spawn(my_io_context,
  echo(std::move(my_tcp_socket)),
  boost::asio::detached);
</pre>
<h6>
<a name="boost_asio.reference.co_spawn.overload4.h2"></a>
          <span class="phrase"><a name="boost_asio.reference.co_spawn.overload4.per_operation_cancellation"></a></span><a class="link" href="overload4.html#boost_asio.reference.co_spawn.overload4.per_operation_cancellation">Per-Operation
          Cancellation</a>
        </h6>
<p>
          The new thread of execution is created with a cancellation state that supports
          <code class="computeroutput">cancellation_type::terminal</code> values only. To change the cancellation
          state, call <a class="link" href="../this_coro__reset_cancellation_state.html" title="this_coro::reset_cancellation_state"><code class="computeroutput">this_coro::reset_cancellation_state</code></a>.
        </p>
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<td align="right"><div class="copyright-footer">Copyright © 2003-2021 Christopher
      M. Kohlhoff<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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